Here is an article I found on CompuServe that tells about a study linking bladder cancer in dogs and lawn chemicals. It's worth a read. Ordinarily, I would just post the link, but unless you've got CompuServe, it's unavailable:

Lawn Chemicals Linked to Dog Cancer

Dogs exposed to lawn chemicals may be four to seven times more likely to develop bladder cancer, according to a new study from Purdue University. Reuters reports that researchers surveyed 83 owners of Scottish terriers whose pets had recently been diagnosed with bladder cancer. "The risk...was found to be between four and seven times more likely in exposed animals," Larry Glickman, professor of epidemiology and environmental medicine in Purdue's School of Veterinary Medicine, told Reuters. "While we hope to determine which of the many chemicals in lawn treatments are responsible, we also hope the similarity between human and dog genomes will allow us to find the genetic predisposition toward this form of cancer found in both Scotties and certain people."

Humans and animals share genes that can predispose them to cancer. Scotties are about 20 times more likely to develop bladder cancer than other breeds. "These dogs are more sensitive to some factors in their environment," Glickman said. "As pets tend to spend a fair amount of time in contact with plants treated with herbicides and insecticides, we decided to find out whether lawn chemicals were having any effect on cancer frequency." He theorizes that if a gene does exist in dogs, it also exists in a similar location on the human genome. "Finding the dog gene could save years in the search for it in humans and could also help us determine which kids need to stay away from lawn chemicals," Glickman added.

The Purdue team's next project is to survey children and dogs in households that have treated their lawns with chemicals and then compare the chemicals found in their urine with those from households that have untreated lawns. The study findings were published in the Journal of the American Veterinary Medicine Association.